The conversion of lignocellulosic biomass has been the subject of intense research efforts since the 1970s (Blumer-Schuette et al., 2008, Extremely thermophilic microorganisms for biomass conversion: status and prospects, Curr Opinion Biotechnol 19, pp. 210-217; Perez et al., 2002, Int Microbiol 5, pp 53-63).
In this regard, it is known to use microorganisms to conduct modification of transformed biomass, essentially pre-treated agricultural feedstocks, to produce bioenergy products such as ethanol. As reported in Mosier et al. (Bioresource Technology 96 (2005) 673-686), however, the pre-treatment of lignocellulosic biomass is required to alter the structure of cellulosic biomass to make cellulose more accessible to the enzymes that convert the carbohydrate polymers into fermentable sugars.
It is believed, however, that future bio fuels or bioenergy products should originate from raw lignocellulosic biomass, instead of from pre-treated agricultural feedstocks. The use of such raw biomass would require an effective method of degrading (e.g., hydrolysing) lignocellulosic biomass into fermentable sugars, which can then be transformed through fermentation into bioenergy products (e.g., alcohols and other metabolites of industrial value). The production of fermentable sugars (e.g., monomeric sugars) from raw lignocellulosic biomass, is therefore a major challenge, and various approaches have been proposed in this regard, such as thermochemical methods, acid hydrolysis and enzymatic hydrolysis.
However, due to the wide range of lignocellulosic biomass being considered, with each having a specific composition of cellulose, hemicellulose and lignin, the development of enzymes or enzymatic compositions for hydrolysing such a raw biomass does not appear cost-effective. In addition, lignin by-products remaining from such treatments of lignocellulosic biomass generally remain unmodified and lost.
WO2009/063079 describes the use of bacteria of the genus Deinococcus for the production of bioenergy products and metabolites through fermentation of biomass.
Taryn et al (ABB 45 (1994) 209) reports the ability of bacteria of the genus Clostridium for degrading fermentable sugars.
WO97/10352 relates to Pseudomonas bacterial strains that degrade cellulose. Similarly, Weon et al (Int. J. Systematic and Evolutionary Microbiology (2007), 57, pp 1685-1688) reports UV-resistant Deinococcus strains which hydrolyse cellulose.
W. Zimmermann (Journal of Biotechnology, 13 (1990) 119-130) provides a review of bacterial degradation of lignin.
Bacteria having the ability to hydrolyse the main constituents of lignocellulosic biomass, including lignin, xylan and cellulose, under conditions suitable for an industrial process, have never been reported. In particular, bacteria which can degrade lignin under industrial conditions have never been isolated.
Accordingly, there is an unmet need for a cost-effective and scalable process for the degradation of lignocellulosic biomass into valuable products such as fermentable sugars or bioenergy products and metabolites.